Compared with the third generation (3G) or fourth generation (4G) communication systems commonly used today, the millimeter wave (mmWave) communication system uses a relatively high frequency band for communication. Since the energy strength of the electromagnetic wave received by the receiver is proportional to the wavelength of the electromagnetic wave signal and inversely proportional to the square of the signal transmission distance, the millimeter wave communication system increases the signal energy attenuation due to the use of the short-wavelength high-frequency signal. In addition, due to the use of high-frequency electromagnetic signals, the ability of transmitting and receiving signals through obstacles in the millimeter wave communication system is reduced. The oxygen and water vapor in the air also absorb the millimeter wave energy. Therefore, in order to ensure the communication quality, transceivers in the millimeter wave communication system usually adopt multiple antenna beamforming technique to improve the problem of signal energy attenuation.
Beamforming is a signal processing technique. Generally an antenna array including multiple antennas is disposed on a base station or a user equipment. By adjusting transmission signals of the antennas, signals at particular angles experience constructive interference, while signals at other particular angles experience destructive interference. The base station or user equipment can thus produce a directional beam, thereby improving the communication quality from the transmitter to the receiver. The benefits of the beamforming technique include energy concentration, increased signal transmission distance. reduced user-to-user interference, and fast data rate. Because the beamforming technique has an important influence on the performance of a millimeter wave wireless communication system, there is a need to provide a system and method capable of performing beamforming calibration in order to achieve a more accurate beamforming result.